Garden of Gems: Montana agate jewelry inspired by the beauty of flowers If you’re like most women, you’re always looking for the perfect gift for your loved ones. And if you’re looking for Designer Jewelry, you’ve come to the right place! We’ve rounded up the best jewelry ideas made with Montana Agate. One of the most beautiful types of agate is the Montana Agate. It’s a colorless stone with inclusions of black, orange, and brown. Most of the Montana Agate is found in the vicinity of the Yellowstone River. The best Montana Agate jewelry styles combine elegance and sophistication with Sterling Silver Jewelry.